ConnectingToOtherDataLoggerTypes / Analogue

Analogue

The analogue outputs also have a low latency. Typically, this is below 2ms. There are 3 analogue outputs, labelled “DAC A”, “DAC B” and “DAC C”. On the standard SPEEDBOX20, longitudinal acceleration is output on A, lateral acceleration on B, and combined speed on C. With the RTK option, yaw is output on A, pitch on B, and combined speed on C.

The analogue outputs nominally output between 0 and 5V but on the SPEEDBOX20, all output values are clamped between 0.5 and 4.5V. On DACs A and B, zero acceleration, yaw or pitch are output at 2.5V. The deflection is governed by the scale set in the configuration software, by default 1g/V for acceleration, and 100°/V for yaw and pitch (yaw and pitch are clamped between -180° and 180°).

The vast majority of the noise on the analogue outputs lies within 1mV of the mean DC output, when sampled at rates between 1 and 100kHz. There may also be noise spikes of extremely short duration on the analogue output caused by cross talk from the pulse output. These are not normally detected by the sampling system due to their short period, but if the analogue outputs are being sampled and the pulse output is not required, it may be desirable to disable the pulse output using the configuration software.